The present invention relates to improved dental power instruments such as endodontic instruments, and a contra-angle drive apparatus or handpiece designed to removably accommodate such instruments.
Dental power instruments are usually provided with a handle, located at an end opposite to the active part of the instrument, for engaging a revolving guiding and gripping device situated in the head of the handpiece. The handle also includes a flat for engaging the profile of a rotary drive housed in the head of the contra-angle, to connect the handle to the rotary drive.
The guiding and gripping device usually includes a retainer, such as a pushbutton or a guillotine, which is controllable by the user. The handle of the instrument is further axially engaged in the head of the contra-angle by a device on the rotating part of the contra-angle which fits into a groove in the handle of the instrument.
Such a system for fixing the instrument handle in the head of the contra-angle requires a great many mechanical parts, which leads to a high cost of manufacture.
Another disadvantage of such a system is that in order to mount the dental instrument in, or to remove the dental instrument from the head of the contra-angle, the practitioner must hold the instrument by its active part. This leads to a risk of contaminating the active part of the instrument, and even a risk of injury to the practitioner, for example, by prick injury.
The object of the present invention is to provide an improvement to such dental instruments that solves some or all of the aforementioned problems by providing an inexpensive way of fitting the instrument to the head of a handpiece shaped to receive such an instrument, while also reducing the risk of contamination of the active part of the instrument and of injury to the practitioner.